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Polarized neutron reflectometry is an experimental method for studying metallic thin heterophase layered materials, polymer films, biological systems, the free surfaces of liquids, and magnetic fluids. It requires experimental equipment that includes a special magnetic system. The magnetic system described in this work, a vector magnet, will allow one to change the direction of the magnetic field in three directions, to place a temperature-control device inside at low and ultra-low temperatures, and will have an aperture that allows one to place a system for detecting neutrons and gamma rays outside. According to calculations, the cryomagnet will allow the application of a maximum field in the vertical plane of up to 3 T, and in the horizontal plane of up to 1 T. To manufacture a vector magnet, in this work, it is proposed to use a tape made of a high-temperature superconductor with a width of 4 mm. A cryostat with a vector magnet will be installed at the REMUR reflectometer on the eighth channel of the IBR-2 reactor. [ABSTRACT FROM AUTHOR]

The results of studying thin films and superlattices of rare-earth helimagnets Dy and Ho using a neutron reflectometer are presented. Neutron reflectometry is shown to allow the magnetic phase transitions in these nanostructures to be studied and information about the periodicity of magnetic helices in them to be collected. It is proposed to create a neutron reflectometer capable of conducting polarization analysis on the DARIA compact neutron source, optimized for studying long-period magnetic ordering in rare-earth helimagnets, and the possible directions of this optimization are indicated. [ABSTRACT FROM AUTHOR]

The possibility of using the resonant scattering of neutrons by gadolinium atoms in the reflectometry of polarized neutrons to determine the interaction potential and calculate the structural and magnetic characteristics of multilayer metal films is considered. The experimental data of polarized-neutron reflectometry for Fe/Cr/Fe films with ferromagnetic and antiferromagnetic ordering of the Fe layers are presented. Using the modulus and phase of the reflection coefficient reconstructed for the studied part of the sample, the structural characteristics and types of magnetic ordering of the layers are determined. Processing is carried out jointly for two scattering channels. For each channel, the modulus and phase are analyzed simultaneously. [ABSTRACT FROM AUTHOR]

The results of studying a superlattice of alternating layers of rare-earth helimagnets [Dy(6 nm)/Ho (6 nm)] × 34 by neutron reflectometry and X-ray diffraction are presented. It is shown that during the growth of helimagnetic structures on sapphire substrates with a Nb buffer layer by magnetron sputtering, the orientational relations Al2O3||(110)Nb|| (Dy/Ho) and the crystal lattices of Nb and the structure of rare-earth helimagnets are completely relaxed. It is also found that two different magnetic helicoids are formed in the sample, propagating coherently in Dy and Ho layers, respectively, with periods and Néel and Curie temperatures that differ from the characteristic temperatures of single crystals and thin one-component Dy and Ho films. [ABSTRACT FROM AUTHOR]

The neutron reflectometry method is used to measure the spatial profile of the potential of interaction between neutrons and a medium. At the interface between media, the interaction potential is the sum of potentials of individual isotopes. Neutrons and gamma radiation emitted by the atomic nuclei of an element are recorded to determine the potential of interaction between neutrons and individual isotopes. Channels for the recording of gamma quanta and spin-flipped neutrons are created using a REMUR spectrometer. Channel testing results are given, model calculations of the neutron absorption coefficients are carried out, and prospects related to the recording of gamma quanta and polarized neutrons are discussed. [ABSTRACT FROM AUTHOR]

In this paper, the results of investigating thin films of rare-earth helimagnetics (REMs) Dy and Ho by polarized neutron reflectometry are presented. It is shown that the growth by magnetron sputtering of rare-earth structures on sapphire substrates with a buffer layer Nb Al2O3||[110]Nb|| leads to complete relaxation of the Nb crystal lattices and the rare-earth film. It is found that some magnetic phase transitions typical of bulk Dy and Ho are not observed in 200 nm [0001]R thin films or are observed in a modified form. Differences between the Néel and Curie temperatures of thin REM films compared to bulk REMs are determined based on polarized-neutron-reflectometry data and measurements of the temperature dependence of the magnetization in the sample plane. [ABSTRACT FROM AUTHOR]

An ionization chamber is installed to the REMUR neutron spectrometer, situated at channel no. 8 of the IBR-2. A layered structure containing a layer of the isotope under study with a thickness of several nanometers is placed into the chamber. A neutron beam enters the chamber and is incident on the structure. The reflected neutron beam and the neutron beam transmitted through the structure are recorded by a detector located outside the chamber. A fraction of neutrons incident on the structure is captured by the nuclei of the isotope under study. As a result, secondary radiation is generated in the form of charged particles, which are recorded by the ionization chamber. The dependences of the neutron and charged particle intensities on the transmitted wave vector of neutrons are used to determine the spatial dependences of the potential of interaction between neutrons with the entire structure and with a layer of the isotope under study. The neutron spectrometer in grazing geometry, using which the neutrons and charged particles are recorded in studying the layered structures, is described. The results of spectrometer testing with the use of structures containing the 6Li isotope are given. [ABSTRACT FROM AUTHOR]

Textured Al-doped ZnO films are studied using neutron reflectometry. The films are quasiperiodic structures with a period of several nanometers. The films are inhomogeneous in a surface layer with a thickness of 10-20 nm. [ABSTRACT FROM AUTHOR]

Examples of the application of a cryogenic moderator in the REMUR time-of-flight neutron reflectometer of the IBR-2 pulsed reactor (Dubna) are given. The results of two experiments are presented: spatial beam splitting upon reflection from a magnetically noncollinear film and the recording of a microbeam formed by a layered waveguide. A conclusion concerning the efficiency of the cryogenic moderator for experiments of this type is made. [ABSTRACT FROM AUTHOR]